He means the Harbormasters Office set, and if I remember correctly, Paul said the third floor is optional. It shouldn't take much to add it in, just use the same procedures you used to make the second floor, just take into account that the roof is one level higher . These parts were also added to make kitbashing the set easier, using the additional walls and floors in places that weren't in the original design or to replace ones that are (like getting rid of a door where one exists, but you don't want one). You can check out Pauls pics, I believe he put together three floors for the pics to show different possible layouts.